Dhe theory is confirmed: a toxic type of algae is responsible for the fish deaths in the Oder. “There is no doubt that this toxin has been detected in all water samples and in significant quantities,” said fish ecologist Christian Wolter of the FAZ on Monday. His colleague Elisabeth Varga from the University of Vienna specializes in the algae species Prymnesium parvum, which was detected in the Oder a few days ago. According to the researcher at the Leibniz Institute for Freshwater Ecology and Inland Fisheries, you discovered the poison. Now it’s a matter of finding out which subspecies it is exactly and how effective the poison is under which conditions.
It was initially unclear whether the algae actually caused the fish to die. It can only spread under certain circumstances and does not necessarily develop toxins. The researcher Elisabeth Varga said: “If this specific type of algae is present in very large quantities, as is the case in the Oder samples, a very high concentration of toxins must also be assumed. Since all samples were taken at an advanced stage of the algal bloom, a direct connection with the death of fish and molluscs can be assumed.” The poison attacks the gills of the fish, suffocating them. Satellite images had confirmed a massive bloom of algae in the Oder on Saturday.
However, the researchers do not assume a natural cause. The alga needs saline water that is stagnant if possible in order to multiply. The conductivity of the water, an indicator of salts in the water, had risen sharply at the Frankfurt (Oder) measuring point around August 7th. Between July 29 and August 10, a Polish company discharged large quantities of salt water from a retention basin into the Oder river near Glogów (Glogau) – with official approval. This may have exacerbated fish kills previously detected 170 kilometers upstream.
Image: dpa
Researchers also discovered a pesticide in river water last week. The values would have clearly exceeded the maximum limit of the environmental quality standard around August 8th. “However, it can be assumed that the dose detected here is not immediately fatal for fish,” said a spokeswoman for the Brandenburg Ministry of the Environment on Friday.
allegations from Poland
On Saturday, Poland accused Germany of spreading fake news. Poland’s Environment Minister Anna Moskwa wrote on Twitter: “Attention, another fake news is being spread in Germany!!! pesticides and herbicides. In Poland, the substance was tested and found to be below the limit of quantification, ie with no effects on fish or other animals and no connection to fish kills.” Another tweet from her said: “The active substance was not detected in the fish. The substance is stored Don’t get bogged down in the fish. Unjustified attack on agriculture. First industry, now agriculture? What next?”
Fish ecologist Wolter said on Monday that a number of pesticides were regularly found in the Oder. They were stored in the sediments of the Oder and would be thrown up during dredging work. Poland is expanding the Oder on the Polish side into a faster waterway, the procedure is controversial in Germany. According to Wolter, the construction work could have released the proven pesticide. The fish absorb the substances, but they are not fatal to them. However, fishermen could no longer sell the animals if the samples exceeded the limits intended for food.
